1. Field of the Invention
The present invention relates to a system for the automatic identification of the type of measuring head of a fiber optic measurement value acquisition and transmission device.
2. Discussion of the Background
A device as supposed in the introductory clause of the claim is known, for example, from "B. Pressley, `Recent Fiber Optic Data Link Developments`, 1986 Nuclear Electromagnetic Pulse Meeting, University of New Mexico".
Fiber optic measurement value acquisition and transmission devices are used for transmitting electric measurement values from an environment with high electromagnetic interference or across relatively great potential differences. The measuring head of these devices is usually fed from an inbuilt battery. The measurement values are transmitted via a measurement signal fiber. In addition to this fiber, another optic fiber is also present in most cases via which the measuring head can be remotely operated by means of control signals from a control unit.
This remote controlling includes the switching on and off of the head, the range selection and the transmission of a calibration signal (typically rectangular) generated in the measuring head.
The control unit can also be designed in such a manner that it can operate various types of measuring head (other measuring ranges and/or input impedances). Appropriate switching over of the control unit is then necessary to match it to the respective type of measuring head. If this is forgotten or carried out wrongly, wrong results can be produced or the measuring head can even be damaged due to mishandling.
Normally, the measuring head can be automatically identified only where, in addition to the measurement value transmission, a bidirectional command and signalling communication also exists between the measuring head and the control unit. However, this makes the entire device more complicated and expensive.